Steering system for trailers

ABSTRACT

A steering system for trailers and other non-powered wheeled vehicles that are pulled or towed. A novel linkage arrangement is provided to turn the wheels of the trailer in response to a turning of the pulling vehicle whereby the wheels of the trailer will track in the same path as the wheels of the pulling vehicle. Further provision is made so that the wheels of the trailer can turn and still clear apparatus or structures on the tractor frame that fit closely between the upper portion of the wheels of the trailer when said wheels are in a straight position.

United States Patent 91 Folkert Aug. 21, 1973 STEERING SYSTEMFOR'TTIIQERS [76] Inventor: Henry Folkert, Rt. 1, Box 107,

Granger, Wash. 98932 [22] Filed: Jan. 3, 1972 [21] Appl. No.: 214,580

[52] 11.8. C1. 280/443, 280/ 103 [51] Int. Cl. B62d 53/00 [58] Field ofSearch 280/443, 444, 445, 280/103, 80, 96.1, 426, 446 R [56] ReferencesCited UNITED STATES PATENTS 1,600,635 9/1926 Isachsen 280/443 2,100,44711/1937 Mahaffey 280/443 2,411,836 11/1946 Seckel 280/80 R 2,559,4877/1951 Whitlow 280/444 2,918,300 12/1959 Hendrickson". 280/80 R2,582,455 l/l952 Potter 280/103 FOREIGN PATENTS OR APPLICATIONS 521,3493/1955 Italy 280/443 1,528,768 5/1968 France 280/443 PrimaryExaminer-Leo Friaglia AttorneyMarvin E. Jacobs [5 7] ABSTRACT A steeringsystem for trailers and other non-powered wheeled vehicles that arepulled or towed. A novel linkage arrangement is provided to turn thewheels of the trailer in response to a turning of the pulling vehiclewhereby the wheels of the trailer will track in the same path as thewheels of the pulling vehicle. Further provision is made so that thewheels of the trailer can turn and still clear apparatus or structureson the tractor frame that fit closely between the upper portion of thewheels of the trailer when said wheels are in a straight position.

8 Claims, 4 Drawing Figures Patented Aug. 21, 1973 2 Sheets-Sheet 1 FIG2 Patented Aug. 21, 1973 2 Sheets-Shoot a BACKGROUND OF THE INVENTIONThe present invention relates generally to steering apparatus fortrailers and other towed or pulled vehicles, and more particularly, toan improved steering apparatus which enables the towed or pulled vehicleto accurately follow the path of the wheels of the pulling vehicle.

In conventional two-wheeled trailers attached to a tractor or automobileby means of the well-known single point ball hitch, it is extremelydifficult if not impossible to cause the trailer to follow the identicalpath of the tractor or automobile, especially on curves and turns. Whilethis is not a serious problem when pulling a trailer or similar typevehicle in conventional street traffic, the problem of having thetrailer wheels track in the same path as the wheels of the pullingvehicle be comes extremely important on narrow, tortuous roads andfarming applications. For example, when pulling a trailer with a tractordown the narrow rows between planted crops, the failure of the trailerto track in the same path as the tractor on a turn between rows ofcrops, could result in the trailer running over valuable crops anddestroying same.

Still another problem encountered with trailers and other pulledvehicles that tend to turn at a sharper radius than the pulling vehicle,is that in farming and other applications, many times it is desirable torun a power take-off shaft from the pulling vehicle such as a tractor tothe trailer to operate a pump, compressor, generator or the like,mounted on the trailer which depends on the power-take-off shaft for itsoperation. In the situation where the trailer turns at a greater radiusthan the pulling vehicle, the angle that the power takeoff shaft must beoperated, at places an extreme strain on the universal joints and theshaft and further requires extremely expensive joints to operate at suchextreme angles.

Still another problem encountered in presently existing trailers bothwith and without steerable wheels, is that in many instances, the wheelson each side of the trailer must be spaced an excessive distance apartin order to clear the particular apparatus carried by the trailer. Whilein some instances it is possible to provide an apparatus such as a tankor a dump bed to be carried on a trailer with recessed openings for thewheels, this is often extremely difficult and expensive to accomplish.In situations where a trailer must be narrow, such as in farming, sothat it will fit between successive rows of crops, the spacing betweenthe wheels on the opposite sides of the trailer become extremelyimportant.

SUMMARY OF THE INVENTION Accordingly, it is the general aim of thepresent invention to provide a new and improved steering system for usewith trailers and other similar non-powered wheeled vehicles that areintended to be pulled which enable the trailer to follow the same pathas the pulling vehicle in a manner that is far superior from thestandpoint of cost, reliability and maintenance than has heretofore beenknown in the prior art.

It is another object of the present invention to provide a steeringsystem of the instant type which enables the wheels on the oppositesides of a trailer provided with the instant system to be spaced closertogether while still clearing an object or apparatus carried by thetrailer than have trailers having steerable wheels heretofore known inthe prior art.

BRIEF DESCRIPTION OF THE DRAWINGS The above stated and other objects andadvantages of the instant invention will readily appear from thefollowing description taken in conjunction with the accompanyingdrawings in which:

FIG. 1 is a bottom view, of an exemplary trailer embodying the featuresof the present invention depicted in use when the trailer is beingpulled in a generally straight direction;

FIG. 2 is a bottom view of the exemplary trailer depicted in FIG. 1, buthere showing the steering system of the trailer responding to a rightturn by the vehicle pulling the trailer;

FIG. 3 is a back fragmentary sectional view taken substantially alongthe line 3-3 of FIG. 1; and

FIG. 4 is a fragmentary sectional view taken substantially along theline 4-4 of FIG. 2.

While the present invention is susceptible of various modifications andalternative constructions, the illustrative embodiment shown in thedrawings will herein be described in detail. It should be understood,however, that it is not intended to limit the invention to theparticular forms disclosed, but, on the contrary, the intention is tocover all modifications, equivalents and alternative constructionsfalling within the spirit and scope of the invention is expressed in theappended claims.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIGS. 1 and 2,a trailer, provided with an exemplaryv steering system, generallyindicated at 10, is illustrated. The trailer, includes a frame 11 and apair of wheels 12 and 14, each independently pivotally mounted onrespectively opposite sides of said trailer, in a manner to behereinafter set forth in detail.

In accordance with one of the important aspects of the presentinvention, wheels 12 and 14 are provided to follow the same track orpath that is traversed by the vehicle that is pulling the trailer 10.This vehicle is generally indicated at 13 in FIGS. 1 and 2. Asillustrated in FIGS. 1 and 2, common tracking of the vehicle 13 and thetrailer 10 is accomplished by a mechanical linkage arrangement whichmakes the wheels 12 and 14 of the trailer 10 turn in response to aturning of the vehicle 15. This linkage arrangement includes a pair ofdrag links 15 and 16, each having one end thereof pivotally attached totheir respective steering control arms 17 and 18 which cause the turningof their respective wheels 12 and 14. The opposite ends of drag links 15and 16 are pivotally affixed to opposite ends of a center pinned singletree 22 which is pivotally pinned at its center to a cross frame member23 of the trailer 10.

In order to pivot the single tree 22 about its center point, therebymoving drag links 15 and 16 the same distance but in opposite directionsresulting in the turning of wheels 12 and 14 in the same direction asshown in FIG. 2, a rigid arm 24 is pivotally mounted between one end ofthe single tree 22 and the draw or attachment bar 26 of the pullingvehicle 13.

It will be readily apparent by referring concurrently. to FIGS. 1 and 2,that since the hitch 27 of the trailer is pivotally affixed to thecenter of the draw bar 26, that when the pulling vehicle 13 turns in aright or left direction, the rigid arm 24 by virtue of being pivotallymounted off center of the draw or attachment bar 26, is shiftedgenerally longitudinally with respect to the trailer 10, therebypivoting the single tree 22 about its center point on frame member 23which as aforesaid, moves drag links and 16 an equidistant amount but inopposite directions thereby turning wheels 12 and 14 in direct responseto the turning of the pulling vehicle 13.

In order to adjust the exemplary steering system to track identicallywith the wheels of the pulling vehicle 13, rigid arm 24 can beselectively mounted in any of the holes 28 provided in the draw orattachment bar 26 for this purpose, and to facilitate said adjustment,it is contemplated that the rigid arm 24 will be provided as beingselectively adjustable as to length by means, for example, of atwo-piece telescoping arrangement with set screws. It is further pointedout that should it not be desired for a particular application, to turnwheels 12 and 14, the rigid arm 24 can be connected at the center of thedraw or attachment bar 26 as depicted in dotted lines in FIG. 1, therebymaintaining the entire exemplary steering system and the wheels in alocked straight position.

It is further pointed out that by running the drag links 15 and 16 fromthe steering control arms 17 and 18 to the single tree in a directiongenerally longitudinal with the trailer 10, the conventional track armand track rod utilized in king pin steering systems is eliminatedthereby leaving the space between the two wheels of the trailer free ofany steering linkage members which could interfere with particularapparatus on structures desired to be mounted on the trailer frame.

In accordance with another important aspect of the present invention,provision is made for simultaneously turning the wheels 12 and 14 whilestill providing clearance with an apparatus or structure mounted on thetrailer frame 11 which fits closely between wheels 12 and 14 when theyare in a straight position as depicted in FIGS. 1 and 3. To accomplishthis, the kingpin 30 is mounted so as to tum at an angle with the planeof the trailer frame as shown in FIG. 3 with the axle stub 31 adapted toproject in the same plane as the trailer frame when the wheels of thetrailer are in a straight position. By locating the king pin 30 at anangle with the plane of the trailer frame 11, the wheels of the trailerwill tend to tilt when they turn with the upper portion thereof beingdirected outwardly from the trailer and the lower portion thereof beingdirected inwardly thereby having the upper portion of the wheel maintainclearance with an apparatus or structure on the trailer that is close tothe upper portion when the wheel is in a straight position.

In practice, it has been found that locating the king pin 30 at an angleof about 45 with the plane of the trailer frame 11, producessatisfactory results however, for particular applications, this anglecould be increased or decreased without departing from the scope andspirit of the present invention.

For example, it has been found that when the king pin 30 is disposed atan angle of about 42 with the plane of the trailer frame 11 as shown inFIG. 3 and in whole lines in FIG. 4, not only do the upper portions ofwheels 12 and 14 tilt away from the trailer thus clearing apparatus orstructures mounted on the trailer frame 1 1 as aforesaid and as depictedin broken lines in FIG. 4, but in addition, at this angle the wheels 12and 14 have an inherent tendency to seek their straight ahead position.Accordingly, this inherent tendency has the desirable result ofminimizing the trailer wandering off to one side of the pulling vehicleor the other if there is excessive tolerance in the steering linkage ofthe trailer. This feature is of particular importance when the traileris being pulled at highway speeds and it has been found that a trailerprovided with this feature of the present invention, can be towed athighway speeds without the rigid arm 24 being utilized or in theaforesaid locked position and the wandering of the trailer both emptyand under load will be far less than that of a conventional two wheeltrailer having its wheels fixed in a straight position.

Turning next to another important aspect of the present invention,provision is also made whereby, if desired, a delay in the turning ofthe wheels of the trailer 10 in response to the turning of the pullingvehicle 13 can be imparted to the steering system of the trailer 10.

This feature finds use, for example, when it is desirable not to havethe trailer 10 start turning until it reaches the same location that thepulling vehicle 13 was at when it started its turn. It will be readilyappreciated that such a situation would occur when the vehicle 13 andtrailer 10 are being utilized in a confined area with adjacent obstaclessuch as rows of crops or the like.

To carry out the aforestated feature, the rigid arm 24 is replaced witharm 32 shown in broken lines in FIG. 2. This arm 32 instead of beingrigid is constructed whereby one portion 33 extends into the otherlarger diameter portion 34 and is free to telescopically slide therein,thereby being capable of effectively changing the overall length of thearm 32 within the range dictated by an elongated slot 35 provided in thelarger diameter portion 34 in which a guide pin 36 affixed to thesmaller diameter portion 33 is located, which as shown in FIG. 2,provides a stop at each end of slot 35 by virtue of the abutment of theguide pin 36 therewith.

It will then be readily apparent to those skilled in the instant art,that if the guide pin 36 is disposed within the slot 35 whereby it is ina mid-position therein when the wheels 12 and 14 of the trailer are in acorrespondingly straight position, upon the turning of the pullingvehicle in either direction, the guide pins 36 will first have to abutone of the ends of the slot 35 before the portion 34 of the arm 32 andthe remainder of the steering system of the trailer 10 operativelyresponds to said turning. Accordingly, by providing a slot 35 ofpredetermined length, a desired amount of lost motion can be built intothe steering system of the trailer 10 so as to delay the turning of thetrialer 10 in response to the turning of the pulling vehicle 13 untilthe trailer reaches the location that the vehicle made its turn on someother desired location. It is further pointed out that the arm 32 can beselectively positioned in any desired location on the draw or attachmentbar 26 in holes 28 provided therefor and/or at any desired location onthe single tree 22 in a similar manner so as to provide a desiredrelationship or ratio between the turning radius of the pulling vehicle13 and the turning radius of the trailer 10.

What is claimed is:

1. A trailer steering system comprising a pair of wheel receiving meanseach pivotally mounted to a trailer on opposite sides of the trailerfrom the other; an elongated steering control arm rigidly fixed to eachof said wheel receiving means and extending generally inwardly from saidwheel receiving means and their respective pivots; a single treepivotally mounted intermediate its ends to the trailer at anintermediate point thereon and at a location remotely spaced from saidwheel receiving means and generally disposed in a directionperpendicular to the direction of travel of the trailer; first andsecond drag links pivotally mounted to and interconnecting each of saidsteering control arms to the side of said single tree that each saidrespective steering control arm is situated; hitch means affixed to oneend of the trailer for attachment to the rearward portion of a pullingvehicle at the generally central portion of the pulling vehicle; and anelongated linkage member having one end pivotally connected to saidsingle tree at a location on said single tree remote from the locationof said pivotal mounting of the tree to the trailer, and the other endof the member pivotally mounted to the rearward portion of the pullingvehicle at a location offset from the position where said hitch means isattached thereto, whereupon on the turning of the pulling vehicle, thesaid elongated linkage member pivotally displaces said single treethereby moving said drag links a generally equal amount but in oppositedirections thereby pivoting said wheel receiving means in apredetermined ratio to the turning of the pulling vehicle.

2. The apparatus set forth in claim 1 wherein each said wheel receivingmeans includes a king pin for pivotally mounting said wheel receivingmeans to the trailer.

3. The apparatus as set forth in claim 2 wherein each said king pin isinwardly and angularly disposed whereby when the trailer is traveling ina generally straight direction, a wheel received by each of said wheelreceiving means will be disposed generally perpendicularly to the groundand when the trailer is in a turning position, the same wheel will bedisposed such that its lower portion tilts inwardly and its upperportion tilts outwardly.

4. The apparatus as set forth in claim 3 wherein each said king pin isinwardly and angularly disposed at an angle substantially 42 with theground.

5. The apparatus as set forth in claim 1 wherein said drag links aredisposed in the same general direction as that of the direction oftravel of the trailer.

6. The apparatus as set forth in claim 1 wherein said elongated linkagemember is adapted to be selectively fixedly positioned at one of aplurality of predetermined lengths whereby the end thereof pivotallymounted to the rearward portion of the pulling vehicle can be so mountedat predetermined distances of offset from the position where said hitchmeans is attached thereto, thereby resulting in selective predeterminedratios of steering between the pulling vehicle and the trailer.

7. The apparatus as set forth in claim 6 wherein said elongated linkagemember includes means to freely expand or contract within apredetermined amount of travel, thereby providing a delay in theresponse of the trailer steering to the turning of the pulling vehicle.

8. The apparatus as set forth in claim 1 wherein said elongated linkagemember includes means freely expand or contract within a predeterminedamount of travel, thereby providing a delay in the response of thetrailer steering to the turning of the pulling vehicle.

* ll i Patent No, 39 Dated August Inventor(s) Henry olker't It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Column 6, line 29, after "means" insert --to Signed and sealed this 8thday of January 1974.

(SEAL) Attes't:

EDWARD M.FLETCHER,JR. RENE D. TEGTMEYER Attesting Officer ActingCommissioner of Patents DRM PO-I 050 (10 69) uscoMM-oc scan-Pea F U45.GOVERNMENT PRINTING OFFICE 2 5'9 0-366-33L 7

1. A trailer steering system comprising a pair of wheel receiving meanseach pivotally mounted to a trailer on opposite sides of the trailerfrom the other; an elongated steering control arm rigidly fixed to eachof said wheel receiving means and extending generally inwardly from saidwheel receiving means and their respective pivots; a single treepivotally mounted intermediate its ends to the trailer at anintermediate point thereon and at a location remotely spaced from saidwheel receiving means and generally disposed in a directionperpendicular to the direction of travel of the trailer; first andsecond drag links pivotally mounted to and interconnecting each of saidsteering control arms to the side of said single tree that each saidrespective steering control arm is situated; hitch means affixed to oneend of the trailer for attachment to the rearward portion of a pullingvehicle at the generally central portion of the pulling vehicle; and anelongated linkage member having one end pivotally connected to saidsingle tree at a location on said single tree remote from the locationof said pivotal mounting of the tree to the trailer, and the other endof the member pivotally mounted to the rearward portion of the pullingvehicle at a location offset from the position where said hitch means Isattached thereto, whereupon on the turning of the pulling vehicle, thesaid elongated linkage member pivotally displaces said single treethereby moving said drag links a generally equal amount but in oppositedirections thereby pivoting said wheel receiving means in apredetermined ratio to the turning of the pulling vehicle.
 2. Theapparatus set forth in claim 1 wherein each said wheel receiving meansincludes a king pin for pivotally mounting said wheel receiving means tothe trailer.
 3. The apparatus as set forth in claim 2 wherein each saidking pin is inwardly and angularly disposed whereby when the trailer istraveling in a generally straight direction, a wheel received by each ofsaid wheel receiving means will be disposed generally perpendicularly tothe ground and when the trailer is in a turning position, the same wheelwill be disposed such that its lower portion tilts inwardly and itsupper portion tilts outwardly.
 4. The apparatus as set forth in claim 3wherein each said king pin is inwardly and angularly disposed at anangle substantially 42* with the ground.
 5. The apparatus as set forthin claim 1 wherein said drag links are disposed in the same generaldirection as that of the direction of travel of the trailer.
 6. Theapparatus as set forth in claim 1 wherein said elongated linkage memberis adapted to be selectively fixedly positioned at one of a plurality ofpredetermined lengths whereby the end thereof pivotally mounted to therearward portion of the pulling vehicle can be so mounted atpredetermined distances of offset from the position where said hitchmeans is attached thereto, thereby resulting in selective predeterminedratios of steering between the pulling vehicle and the trailer.
 7. Theapparatus as set forth in claim 6 wherein said elongated linkage memberincludes means to freely expand or contract within a predeterminedamount of travel, thereby providing a delay in the response of thetrailer steering to the turning of the pulling vehicle.
 8. The apparatusas set forth in claim 1 wherein said elongated linkage member includesmeans freely expand or contract within a predetermined amount of travel,thereby providing a delay in the response of the trailer steering to theturning of the pulling vehicle.